This Wednesday, April 23, 2014 photo provided by Google shows the Google driverless car navigating along a street in Mountain View, Calif. The director of Google’s self-driving car project wrote in a blog post Monday, April 28, that development of the technology has entered a new stage: trying to master driving on city streets. Many times more complex than freeways, which the cars can now reliably navigate, city streets represent a huge challenge. (AP Photo/Google)

LOS ANGELES — Google says that cars it has programmed to drive themselves have started to master the navigation of city streets and the challenges they bring, from jaywalkers to weaving bicyclists — a critical milestone for any commercially available self-driving car technology.

Despite the progress over the past year, the cars have plenty of learning to do before 2017, when the Silicon Valley tech giant hopes to get the technology to the public.

None of the traditional automakers has been so bullish. Instead, they have rolled out features incrementally, including technology that brakes and accelerates in stop-and-go traffic or keeps cars in their lanes.

“I think the Google technology is great stuff. But I just don’t see a quick pathway to the market,” said David Alexander, an analyst who specializes in autonomous vehicles.

Casey Neistat admits that the logistics of running a business isn’t his speciality. Instead, he shared with Denver Startup Week audiences how he went from high school dropout to an HBO show, a New York Times partnership and later, an app that got started while on a fellowship at the Massachusetts Institute of Technology.

Twitter is defending its decision not to remove a controversial tweet by President Donald Trump on Saturday that targeted North Korea, in a six-tweet response to critics who argued that Trump violated the platform’s rules.